The invention relates generally to semiconductor integrated circuits, and more particularly, to an apparatus and method for forming metal (e.g., solder) bumps onto a surface of a semiconductor integrated circuit, such as a spherical-shaped semiconductor device.
Conventional integrated circuit devices, or "chips," are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface. Once completed, the wafer is then cut into one or more chips and assembled into packages. Usually, electrical connections are made inside the packages from the input and output pads of the chip to the input and output pins or leads of the packages. Thereafter, the packages are secured to a circuit board or seated into reception sockets which can then be soldered to the circuit board. There are many different types of packages, including solid lead packages (e.g., PDIP, SOJ), and various solder bump packages (e.g., flip chip). For the solder bump-type packages, solder bumps make electrical connections directly between the chip and the circuit board or the reception socket.
In U.S. patent application Ser. No. 08/858,004 filed on May 16, 1997, a method and apparatus for manufacturing spherical-shaped semiconductor integrated circuit devices is disclosed. One way to connect the spherical shaped semiconductor devices to packages or circuit boards is to use multiple micro metal balls or stud bumps at certain areas of each spherical shaped semiconductor device. This can be an expensive process since not only do the stud bumps or micro metal balls have to be manufactured separately, additional steps must be taken to carefully connect them to predetermined locations of the spherical shaped semiconductor device.
What is needed is a system and method for effectively and economically forming solder bumps on a surface of a semiconductor integrated circuit, such as a spherical-shaped semiconductor device.